Effect of nutritional deprivation (malnutrition) on the CNS development will be studied in neural tissue cultures. Mouse CNS explants will be cultured in media deficient in fatty acids, ketone bodies, thyroid hormone and/or glucose, and the state of development (myelination and synapse formation) will be evaluated by morphological (silver impregnation and electron microscopy) and biochemical parameters in these cultures. Our study should establish "critical" concentrations of these substrates in the medium in which CNS explants exhibit normal developmental patterns. One long-term goal is to determine the "optimal" nutritional and growth requirement of the CNS cultures and to develop a totally defined medium. In dissociated neuron cultures, cytochemical localization of acetylcholine receptors and nerve growth factor receptors will be studied. When neuronal plasma membrane receptor sites are identified and demonstrated, turnover of receptor sites (redistribution and internalization) will also be probed. As adult mouse sympathetic neurons are available, these neurons will be tested for the change of receptor distribution as a function of age (vs. young neurons from newborn animals).